Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS48 KWNS 260845
SPC AC 260843
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CDT Sun Mar 26 2017
Valid 291200Z - 031200Z
...Day4/Wed - TX/OK/LA/AR...
The upper system that is expected to result in severe weather over
west TX on Tuesday will track eastward and affect the Arklatex and
adjacent areas on Wednesday. 00z model guidance is in good
agreement on the timing of a shortwave trough rotating across TX and
into the mid MS Valley during this period. Ample low level
moisture/instability and strong wind fields indicate a risk of an
active severe weather day capable of large hail, damaging winds, and
a few tornadoes. The ECMWF solution suggests that some risk of
strong storms extends northward into MO/IL, but will defer to later
outlook updates to refine this threat.
...Day5/Thu - LA/MS/AL...
Models begin to show significant divergence of solutions on
Thursday. The GFS suggests a strong shortwave trough and associated
low-level jet will move from LA to GA during the period. Meanwhile,
the ECMWF/UKMET solutions indicate the system tracks more
northeastward into the OH Valley. An overlap of these two scenarios
provides sufficient confidence to add a 15% risk area for parts of
LA/MS/AL. This area is also consistent with 12z ECMWF ensemble
...Day7/Sat and Day8/Sun - OK/TX/LA...
Another strong upper trough is forecast to move into the southwest
states by Saturday, leading to another emerging risk of severe
storms. Models are inconsistent in the timing and location of this
trough, so will not attempt to forecast a 15% severe area at this
time. However, it is likely that parts of the TX/OK/LA region will
be included in later outlook updates.